The Food and Drug Administration has granted Orphan Drug designation to TransCon hGH (lonapegsomatropin; Ascendis Pharma), a long-acting prodrug of somatropin, for the treatment for growth hormone deficiency (GHD).

The investigational agent is being developed as a once-weekly treatment; currently approved formulations of somatropin for pediatric GHD are administered as daily subcutaneous injections. Using proprietary technology (TransCon™ or “transient conjugation”), the Company is able optimize the therapeutic effect and dosing frequency of somatropin, shielding the parent drug from clearance by binding it to an inert carrier. Once injected into the body, the parent drug is released and is expected to maintain the same mode of action.

TransCon hGH was evaluated in a phase 3 trial (heiGHt) that included 161 treatment-naïve children with GHD. Patients were randomized 2:1 to receive either once-weekly TransCon hGH or daily hGH (Genotropin; Pfizer) for 52 weeks. Results showed that once-weekly treatment with TransCon hGH was superior to once-daily hGH on the primary end point of annualized height velocity (11.2cm/year with TransCon hGH vs 10.3cm/year with daily hGH; treatment difference: 0.86cm/year; 95% CI, 0.22-1.50; P =.0088). In addition, no serious adverse events were reported in either arm.

“As the only long-acting growth hormone product in development that delivers somatropin, we believe TransCon hGH has significant potential to improve patients’ lives,” said Dana Pizzuti, MD, Ascendis Pharma’s Senior Vice President of Development Operations. “We remain on track to file our marketing applications for TransCon hGH in the US and Europe, as planned, in the second and fourth quarters of this year, respectively.”

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The Company is also working on an investigational autoinjector for TransCon hGH. The autoinjector delivers a single, low-volume injection via a small needle and allows for automatic data capture and integration with a connected healthcare system.

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